Nikon B500 has a
16.0MP 1/2.3 (6.17 x 4.55 mm ) sized BSI-CMOS sensor . On the other hand, Nikon P90 has a
12.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the B500 and P90 sensor size comparison.
Nikon B500 and Nikon P90 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.